/*
 * Copyright (c) 1997-2018 Oracle and/or its affiliates. All rights reserved.
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package cn.taketoday.expression;

import java.lang.reflect.Method;

/**
 * The interface to a map between EL function names and methods.
 *
 * <p>
 * A <code>FunctionMapper</code> maps <code>${prefix:name()}</code> style
 * functions to a static method that can execute that function.
 * </p>
 *
 * @since JSP 2.1
 */
public abstract class FunctionMapper {

  /**
   * Resolves the specified prefix and local name into a
   * <code>java.lang.Method</code>.
   *
   * <p>
   * Returns <code>null</code> if no function could be found that matches the
   * given prefix and local name.
   * </p>
   *
   * @param prefix
   *         the prefix of the function, or "" if no prefix. For example,
   *         <code>"fn"</code> in <code>${fn:method()}</code>, or
   *         <code>""</code> in <code>${method()}</code>.
   * @param localName
   *         the short name of the function. For example, <code>"method"</code>
   *         in <code>${fn:method()}</code>.
   *
   * @return the static method to invoke, or <code>null</code> if no match was
   * found.
   */
  public abstract Method resolveFunction(String prefix, String localName);

  /**
   * Adds a static method that can be used as a function.
   *
   * @param prefix
   *         the prefix of the function, or "" if no prefix. For example,
   *         <code>"fn"</code> in <code>${fn:method()}</code>, or
   *         <code>""</code> in <code>${method()}</code>.
   * @param localName
   *         the short name of the function. For example, <code>"method"</code>
   *         in <code>${fn:method()}</code>.
   * @param meth
   *         The static method that is to be invoked, when the function is
   *         referenced. The null value causes the function to be removed from
   *         the map.
   *
   * @since EL 3.0
   */
  public void mapFunction(String prefix, String localName, Method meth) {

  }
}
